This intimidating-looking word simply means “fish-eating.” One of Noah Webster’s goals for the first edition of the 1828 American Dictionary of English Language was to simplify certain language concepts, and this word actually achieves that goal by creating a word from basic Greek roots. Its first appearance was in Webster’s dictionary — it’s formed from the two Greek combining forms “ichthyo-” (“relating to fish”) and “-phagous” (“feeding on a specified food”).